ENHANCED PHOTOLUMINESCENCE OF Eu(III)-ANCHORED POROUS ANODIC ALUMINA FILM

We report here the enhanced luminescence of Eu(III)-anchored porous anodic alumina prepared by self-assembling Eu(III) acetylacetonate, and investigate the luminescence mechanisms. Porous anodic alumina can emit visible light due to a lot of oxygen vacancies formed in the anodic oxidation. The existence of oxygen vacancies resulted in e^?-h⁺ pairs when excited. Eu(II) exists stably by forming Eu²⁺-hole complexes. The enhanced luminescence of Eu(III)-anchored porous anodic alumina is attributed to the complex luminescence of e^?-h⁺ through luminescence center Eu²⁺.     

Fire retardancy of polyethylene‐alumina trihydrate containing clay as a synergist

The fire behavior of polyethylene combined with alumina trihydrate (ATH) and an oligomerically‐modified clay has been studied. The combination of polyethylene with 2.5% inorganic clay and 20% ATH gives a 73% reduction in the peak heat release rate (PHRR), which is the same as that obtained when 40% ATH is used alone. A further increase in the clay loading does not improve the fire properties. Mechanical properties, such as elongation at break, can be improved in comparing compounds with or without clay at the same reduction in PHRR. The oligomerically‐modified clay can also facilitate the melt blending process. Copyright © 2005 John Wiley & Sons, Ltd.     

Formation of Superhydrophobic Alumina Coating Films with High Transparency on Polymer Substrates by the Sol-Gel Method

Transparent, superhydrophobic coating films have been prepared on polymer substrates at low temperatures through the sol-gel method. Al₂O₃ gel films were prepared on poly(ethylene terephthalate) substrates from Al(O-sec-C₄H₉)₃ chemically modified with ethyl acetoacetate. A small roughness of about 20–50 nm was found to form on the surface of the Al₂O₃ gel films dried at room temperature and then immersed in hot water at 60°C. The electron diffraction measurements have shown that this roughened surface consists of pseudoboehmite nanocrystals. The coating of hydrolyzed fluoroalkyltrimethoxysilane on the Al₂O₃ gel films with the small roughness produced transparent, superhydrophobic films with contact angle for water larger than 150°.     

Reversible chemisorption of carbon dioxide: simultaneous production of fuel-cell grade H2 and compressed CO2 from synthesis gas

One vision of clean energy for the future is to produce hydrogen from coal in an ultra-clean plant. The conventional route consists of reacting the coal gasification product (after removal of trace impurities) with steam in a water gas shift (WGS) reactor to convert CO to CO₂ and H₂, followed by purification of the effluent gas in a pressure swing adsorption (PSA) unit to produce a high purity hydrogen product. PSA processes can also be designed to produce a CO₂ by-product at ambient pressure. This work proposes a novel concept called “Thermal Swing Sorption Enhanced Reaction (TSSER)” which simultaneously carries out the WGS reaction and the removal of CO₂ from the reaction zone by using a CO₂ chemisorbent in a single unit operation. The concept directly produces a fuel-cell grade H₂ and compressed CO₂ as a by-product gas. Removal of CO₂ from the reaction zone circumvents the equilibrium limitations of the reversible WGS reaction and enhances its forward rate of reaction. Recently measured sorption-desorption characteristics of two novel, reversible CO₂ chemisorbents (K₂CO₃ promoted hydrotalcite and Na₂O promoted alumina) are reviewed and the simulated performance of the proposed TSSER concept using the promoted hydrotalcite as the chemisorbent is reported.     

Coating of Sol Particles for Membrane Applications

For improving chemical and thermal stability of γ-Al₂O₃ membranes boehmite (AlOOH) sol-particles are coated with Zr⁴⁺-species with two techniques. These techniques are heterogeneous precipitation (HP-method) and “surface-reaction-followed-by-polycondensation” (SRPC-method). A continuous coating layer is formed at relative low Zr⁴⁺-concentration, about one monolayer coverage of boehmite particles, and with the HP-method. For large concentrations and for the SRPC-method small particles (order 1 nm) of Zr⁴⁺-species are formed on the surface of the boehmite particles. After drying and calcination up to 1000°C no continuous layer of a zirconia phase could be detected for all samples. However the thermal stability of the porous structure is improved. Phase transitions of alumina occur at temperatures of 1100°C and the porous structure of the membrane material is then destabilized.     

Characterization of polymer-coated silica particles by microelectrophoresis

Electrophoretic mobility measurements have been used to characterize monodispersed colloidal particles of silica, silica coated with alumina (cores), of these cores incorporating a dye (pigments), and finally of pigments coated with polymers. The latter consisted of poly(divinylbenzene), of poly(vinylbenzyl chloride), and of their copolymers, synthesized directly on the core or pigment particles, with and without subsequent sulfonation.     

12－硅钨酸与γ－Al_2O_3载体表面的相互作用

研究了不同溶剂中ＳｉＷ１２在γ－Ａｌ２Ｏ３表面的吸附和溶脱规律，以ＩＲ，ＸＲＤ以及酸催化模型探针反应对吸附于γ－Ａｌ２Ｏ３表面的ＳｉＷ１２的存在形态和酸性进行了表征．尽管ＳｉＷ１２碱降解稳定性在常见杂多酸中最强，但由水溶液中吸附在γ－Ａｌ２Ｏ３表面的ＳｉＷ１２仍有一部分被该载体的碱性所降解．此外，在γ－Ａｌ２Ｏ３表面上ＳｉＷ１２质子的活动性大大减弱，其阴离子的热稳定性也明显降低．可以认为，ＳｉＷ１２的质子和Ｋｅｇｇｉｎ阴离子与γ－Ａｌ２Ｏ３表面均有直接相互作用．     

Recent trends of industrial catalysts for resid hydroprocessing in Japan

To meet the gradual changes in petroleum demand, in particular a reduced demand for heavy fuel oil, advanced technology for resid hydroprocessing is now extremely necessary. The catalyst technology for resid hydroprocessing in Japan, especially fixed bed type of hydrodesulfurization and hydroconversion, is reviewed in this article.     

Secondary electron emission of sputtered alumina films

Secondary electron emission yieldδ was measured for thin films of alumina prepared byrf sputtering technique. Single pulse method was used along with 4-gridleed optics system to determineδ. Maximum value of 4·3 was obtained at primary energy of 350 eV. The Dionne’s theory was used to analyse the results and the emission probability escape depth and absorption coefficient of secondaries were also estimated. Fairly good correlation is observed between experimental and theoretical values ofδ for beam energies upto 1 keV.